For anyone using TurboTax for Mac this year, there is a serious bug in calculating 529 plan qualified distributions. It appears to be marking them as unqualified and taxing them.

If I enter the qualified expense, tax goes up, set it to zero, goes down, set it back to the original value, it goes up. Delete the value it goes away, tax goes down. The original value comes back, but the tax does not go up.